What is a Virus in Simple Terms?

By John King, CISSP, PMP, CISM •  Updated: 01/01/23 •  3 min read

A computer virus is a kind of malicious software designed to infect and infiltrate computer systems, often without the knowledge or consent of the user. Once a computer is infected with a virus, it can spread the virus to other computers through various means, such as email attachments, instant messages, and file sharing.

There are many different kinds of computer viruses, and they can have a wide range of effects on infected systems. Some viruses are designed to replicate and spread, while others are more sophisticated and may have specific goals, such as stealing sensitive information or altering system configurations.

One of the primary ways that viruses spread is through email attachments. It is common for viruses to be disguised as legitimate files, such as documents or pictures, and then sent to a large number of recipients in an attempt to infect as many computers as possible. It is essential to be cautious when opening email attachments, especially if you are not expecting to receive a file from the sender.

Instant messaging and file sharing are also common methods of virus transmission. File-sharing programs, such as peer-to-peer networks, can be a particularly effective way for viruses to spread, as users may be more likely to download files from these types of networks without thoroughly checking the content of the files.

There are several different types of computer viruses, including:

To protect against viruses, it is important to use up to date antivirus software.. It is also important to be cautious when downloading files from the internet or opening email attachments and to avoid visiting potentially malicious websites.

In addition to antivirus software, other measures can be taken to protect against viruses. These include:

In conclusion, computer viruses are a significant threat to computer systems and can cause many problems for infected users. It is essential to protect against viruses, such as using antivirus software and being cautious when downloading files or visiting websites. By following these precautions, you can help to reduce the risk of your computer being infected with a virus.


John King currently works in the greater Los Angeles area as a ISSO (Information Systems Security Officer). John has a passion for learning and developing his cyber security skills through education, hands on work, and studying for IT certifications.